Delfland is one of our country's twenty-four water authorities. The area in which Delfland operates is bordered by the North Sea, the Nieuwe Waterweg and the Berkel en Rodenrijs line, Zoetermeer and Wassenaar. On an area of 41,000 hectares, about 1.4 million people live and work, and approximately 40,000 businesses are established. This makes the Delfland region one of the most densely populated and most highly industrialized areas of the Netherlands. The region is furthermore renowned for its intensive glasshouse horticulture.
The three key tasks of Delfland - maintenance of dikes and dams, water level control, and water quality control - initially do not seem to have much in common. But you can't tell a book by its cover. Often you cannot view one task separate from the other. The manner in which you construct and maintain quays, for example, has consequences for the quality of the water. Which is why Delfland always performs its tasks with "a broad view". In other words: taking into account all possible relevant factors. This is also known as integrated water management. To that end, Delfland strives for cooperation with other authorities and institutions.
A good execution of the key tasks, cooperation and consideration for nature; these are the three directives of Delfland's policy. The Water authority thereby does not limit itself to the struggle against water, but also for water. Because no water means no life. Water is life!
The Delfland region is located far below sea level. And if a dune or dike should give way, the land behind it would flood. The consequences of a collapse in the Delfland region would be felt as far as the Utrechtse Heuvelrug. To limit the danger, Delfland maintains the sea and river flood defence structures and quays. Safety is, of course, crucial in the management and maintenance of the dikes and dams. But, in addition to safety, the past few years have also seen increasing attention being devoted to the landscape, nature and recreation.
The main or so-called primary maintenance of dikes and dams consists of two components: the seawall and the river flood defence structure. This primary maintenance of dikes and dams of Delfland must be able to withstand a wind-force and water level which, on average and statistically speaking, do not occur more than once every 10,000 years.
Water management involves the regulation of the water level in streams, lakes, ditches, moats and canals. This is vital for developments, agricultural businesses, the shipping industry, nature and recreation. The height at which the water level of an area is set depends on the use and function of that area. The level in wildlife areas, for instance, often fluctuates, while farmers prefer a relatively low water level to prevent their land from becoming too wet. The management of water levels is also of great importance for the shipping industry. If the water level is too low, large ships will run aground; if it is too high, the vertical clearance under bridges will become insufficient.
Delfland ensures an optimum quality of the surface water in its management region. This key task entails the purification of wastewater and the limiting of discharges into surface water wherever possible. After all, clean and pure water is important to humans, but also to animals and plants. Delfland therefore creates conditions that lead to a better-optimized habitat for plants, aquatic plants and animals. This can be done by constructing nature-friendly banks for example, or through ecological maintenance of waters and quays.
Water authorities are, just like municipalities, local authorities. But unlike municipalities, water authorities are functional authorities. This means that the Water authority has specific tasks and that the implementation of these tasks is financed through taxes. These taxes are imposed on residents and companies within the management region. There is a separate tax for each task to be carried out. These include pollution tax, water board levies, sufferance tax and legal dues.